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I am trying to set up a 3d 1h detected exp in solid. working on 700 MHz spectrometer,with a 3.2 mm probe. normal zg on 13c, is good ( so sample is fine). the problem occurs that i have two cp( cross polarisation) transfers steps in my 3d exp, I am not able to get 1D 1H signal out of 3d exp.the exp with the cp works well on 600 MHz spectrometer though. is it a probe problem or a magnetic field inhomogeneity? any clue will be appreciated. |
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Hello, ... may be the internal cabling/routing went wrong? Have a look on this with the command "edasp", there you click than on the "Default"-button. Which kind of probe do you use? Which pulsprogram do you use? Varian, JEOL or Bruker? Ok, you gave a hint, with "zg" it is a Bruker one! 3d are measured normally as proton detected ones - inverse probes! solid state is a direct detection one, less proton sensitivity and there are filters in the HPPR, to stop protons in the x channel. Please remember this, and this is the reason to look on the internal wiring scheme with "edasp". Please give us a note, what are you doing. Yours sincerely, Ulrich Haunz |
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IF the hardware has been set up properly and if the CP experiment works at 600 MHz, it would be worthwhile to check the line-widths in both proton and carbon spectra. Increase in linewidth at 700 MHz may be due to sample heating, inadequate rotor speed, chemical exchange effects, altered CSA term, etc. and may be indicative of a significantly altered effective relaxation time for protons/carbons. Cross polarization experiments are sensitive to relaxation times of both protons and carbons. IF the relaxation time in the rotating frame is shorter at 700Mhz than at 600MHz, then repeating the experiment with a shorter CP time, or at lower magnetic field may be beneficial. |
Hello, please edit the title of your question so that it makes better sense. - Evgeny Fadeev (Feb 21 '13 at 06:44)
I have changed the heading. - anupc (Feb 22 '13 at 04:16)